Hi,
Thank you for adding me to this forum.
I am considering buying the Tormek T4, because the T8 is a bit expensive for me, considering I am just doing some woodworking for a hobby.
Having said that, on the other side, I do not wish that after some time using the T4, I will regrade that I didn't bought the latest model, T8, considering that the T4 is a more older model, probably soon the be replaced.
There are some issues that I wish to get advice upon please:
Is the size of the grinding wheel (200 x40mm) a drawback compared with the T8 250x 50mm
Also the dealer, from whom I am thinking of buying, has this (part of ) description
SG 200 Super-Grind-Stone 200 x 40 mm
Genuine leather honing wheel 145 x 26 mm
Motor 230 V, 120 W (input)
Duty max. 30 min(hour)
Running speed 120 rpm (idling)
Now, can anybody explain the underline sentence what does it means. My impressions is that the T4 can't be used more than 30 min constantly, so if this is what I think it is, then the motor is not so heavy-duty, as much as I wish it to be.
I also made some searching for an alternative model, just to compare and I found the RECORD POWER WG250 wet grinding machine for €299, with 5 years guarantee close to the T8 in specs, 250x50mm wheel, and with variable speed/stepless speed, but not refined as the T8, IMO.
Before I decide I wish that I get some good advice from those who have experience in this machines.
Thank You for your help.
Alf.
Hi Alf, I cant talk to the T4 to T8 specifically as I have the T7... but I am sure Ken will be along soon who can give good answers on that.
BUT Duty cycle I can talk on, it is standard for all machinery to have a duty cycle, this is often down to heat generated and the effects of that heat on the machine, a 50% duty cycle is pretty good for the type of machine it is, and more than adequate for your use, as if you are spending more than 50% of your time on sharpening that means you are spending less than 50% of your time woodturning which is not your intention.
People who just sharpen things all day long would possibly have an issue with it that is why bigger motors with more heat handling materials exist.
Dear Dusmif, please consider the slogan that I try to live by. "You can use less of more but you cannot make more of less". Specifically, the T4 while probably more than adequate for your needs will never last as long as the T8 for one simple reason. The stone begins life 50 mm smaller in size. All other things being equal that is the difference. I am of course referring to stone life itself and not anything else. The frame and accessories will outlast you or I under the circumstances you indicated. A little hobby sharpening will not wear out the T4. The T4 is by the way, an upgrade and a huge upgrade over its predecessor the T3. The T3 had a plastic frame and was not nearly as robust as the T4. I would not hold my breath waiting for an upgrade to the T4. The T3 with its plastic frame had a limited continuous run time because the plastic frame could not withstand the heat of continuous running like a metal frame. I do not know if the actual motor is less robust than that on the T8. 30 minutes run time is a pretty long time. You should be able to sharpen anything that is just dull within that time. Reshaping is another matter as is repairing a damaged edge. Also, remember this old saying, "when is the last time you regretted buying the best"? I would stay away from copy cat machines and buy the original.
Alf,
If you search "alan holtham Tormek T4 video" you will find Alan Holtham's well done video on the T4. You should study this.
The T4 and T8 are almost identical. Granted, the T4 uses 200mm grinding wheels and the T8 uses 250mm wheels. The water trough on the T8 can be raised and lowered.
They share a common handbook. All of the Tormek jigs work with either model. The T4 has a 120 watt motor; the T8 has a 200 watt motor. To put this difference in perspective, if you drive in a small town for work and grocery shopping, do you really need a full size pickup truck with a large V8 engine?
The 30 minute motor duty story is a left over from the T3. The T3 had an all plastic housing which retained the motor heat. With continuos use, the all plastic housing could melt. Tormek corrected this problem with the redesigned zinc top for the T4. It improved precision and acted as a radiator, keeping the machine cool. You will need a work break long before your T4 might need one. Incidentally, Tormek incorporated the machined zinc top into the T8. The T4 is not an "older model"; it is the first introduced of Tormek's latest models.
When the T4 was first introduced, we had posts suggesting the plan of starting with the T4 and moving up to a T7/8. I don't know of anyone actually doing that. There is nothing wrong with the T8. I use both a T4 and a T8, and could be happy owning just one, either one. In the long run, I believe your intended use and work environment are more important factors than price. In my case, I appreciate the lighter weight of the more portable T4. In a large shop, where the Tormek was rarely moved, this would not matter.
A key factor for me is quality. Tormek has an almost fifty year reputation for quality and longevity. We have many Tormeks still in regular use on this forum which are more than fifteen years old. I can't comment on any other brands of wet grinders, as I have never used any. I can confidently state that I expect my Tormeks, including my T4, to last for many more years.
Ken
Alf and Jeff,
Watch this you tube. He is a prime example of someone who really needs a larger size Tormek (in his case, a very old used SuperGrind):
https://youtu.be/8zQDmQ_n7wg
Jeff, I agree that the larger T8 grinding wheel will last longer. However, replacement wheels for the T4 are considerably less expensive. I think the two factors balance each other out.
I completely agree with your last two sentences.
Twisted Trees, in the US we have a saying supposedly by Abraham Lincoln about spending most of the allotted hours sharpening an axe to cut down a tree. (It does not speak highly about his sharpening ability.) I would also be dubious of a turner who spent half his turning time sharpening his tools. :-\ It doesn't make turning sound like much fun.
The key to efficient reshaping with the Tormek is using the right wheel. There are several good choices available for the T4. Tormek makes the DWC-200 and DWF-200 diamond wheels. They are marketed just for the T2, but work perfectly with the T4. There is a variety of non Tormek CBN wheels, which work very well. There is also the Norton 3X option, much firepower at a low cost. In my opinion, any of these options work better than the missing SB blackstone.
Ken
Hi All,
Thank you All for time and advice. Much appreciated.
I do not wish to sound a pain in the head, but recent visit to Tormek home site ( link found at the top of this Form ) I found some interesting and worrying information, at least to me, maybe due to my inexperience in this matter/Subject. This copy and paste of the wording.
" The T-4 is ideal for grinding chisels, knives and smaller tools, such as: B. carving tools. It can also be used for turning tools and drills, but for planing knives and profilers we recommend one of the larger Tormek machine models. Note that due to the Tormek T-4's compact size, some forms of lathe tools can not be removed with the SVD-186 on the leather puller. These tools can be deducted freehand.
The engine is designed for 30 minutes of uninterrupted operation. This is usually more than enough for home use, but if your sanding needs are higher you should consider purchasing one of the larger Tormek models as they are designed for continuous operation."
Now, it is not my intention to spend most of my time in the workshop sharping my tools, far from that, and the 30 min time limit does not bother me, especially after the clear explanation why it has the time limit for continuous use. and that is why I was interested in the T4 because the T8 is overkill for me, not to mention the cost.
But since I have the Emco Star woodworking machine with its' planner I was hoping that at least with this investment I can sharpen my planner knives too, along my chisels and hand planner blades, which it seems that I may have some problems with the T4 to do that.
With that statement I got worried that the motor is is modest to the T8 motor.
As Jeff said "You can use less of more but you cannot make more of less", that I learned the hard way from past experience. That is why I am seeking your advice here.
I am sure that all my worries are due to lack of experience regarding this machine, so, I should not be misunderstood that I am carping the Tormek.
If anybody has any experience with Planer Blade Attachment SVH-320 on the T4, I will appreciate very much your feedback.
Again thank you for your help.
Alf
I don't have experience with the SVH-320 on a T-4, but I do own a T-4 and chose it specifically for its size and portability over the T-8.
The higher price of the T-8 was not a factor for me, since I feel that it's very clear what you're getting extra for the price difference. Usually, I go for the absolute best, but I realized that I just don't have the space for a T-8, and will be using the T-4 only casually. To me, it sounds like you are a more dedicated hobbyist woodworker, and would possibly be benefiting from a T-8, also given the tools that you mention. Note that the T-8 should come with a water chute for long tools (convenient when sharpening your planer blade), has a magnet in the water trough to catch metal particles and comes with both a TT-50 and SE-77 in the box, in addition to the advantages already mentioned in this thread. I had to buy the TT-50 (mandatory purchase) and SE-77 accessories separately which brings the price difference between the T-4 and T-8 (at least in my country) to an acceptable €160, which IMHO is completely worth it.
IMHO size/weight of the T4 and T8 are only relevant if you are going to move them regularly, like daily. If you have a dedicated space for either, size/weight is not an issue that needs consideration. I did some checking on Amazon for stone prices and did some math on the stone sizes. SJ 250 in volume is 3.14 x 125mm² x 50mm= 2453 cm³. The SJ 200 is 3.14 x 100mm² x 40mm= 1256cm³. 1256/2453=51% So the SJ 200 is one half the size of the SJ 250, roughly. Cost on Amazon could be as low as $116 for the SJ 200 and $191 for the SJ 250. 116/191=61% The cost of the T4 is as low as $415 and the T8 as low as $719. This represents the "base" model of each and was searched using "low to high". $415/$719= 58% The two machines represent two different values according to my calculations. The T4 is about half the cost of the T8. Is it actually "half" the machine in longevity and usefulness is yet to be decided. We do know its size will preclude its ability to sharpen some items as Dismuf discovered. The T4 is half the cost initially and half the cost for consumables. The jigs are the same cost. The prospective consumer just needs to decide if they want half of a machine for half the money. Another way to look at is will the T8 do twice the work? If you never sharpen a planer knife or a profiler then perhaps the T4 is good enough. On the subject of portability it should be noted that both machines require that they be situated at or below the waist for ease of use. In either location you are not so much picking up weight as you are just holding weight. It is easier to hold weight than pick it up or elevate it. IE you can stand and hold 100 lbs even though you may not be able to pick it up from the ground. I do not think the T4 is only half of a T8 but it is less. You must decide if less of more is good enough for you and your needs.
Actually, the cost / cm3 is lower for the T4 grindstone when looking at the cost per useful cubic cm (23-30% lower). I plotted it out on the chart that I've attached below.
The only real limitation to the T4 over the T8 (IMHO) is that there is no availability of the following grindstones:
- SB - Blackstone Silicone
- Diamond
Now, that said,
- I worked for many years using only the SG original grindstone, and
- I have had a Tormek T-2000 since 2002, and still haven't seen the need to invest in the diamond wheels.
Since you use the same jigs for all Tormek machines, I would advocate that you are better off getting started with a T4 than fighting whatever method you are using now. At some point later, you may choose to "upgrade" to a larger machine; or you may be entirely happy with the T4 for the rest of your days.
Good luck,
Rich
Yes, but doesn't the new water trough with the ability to raise the height of the trough allow you to use more of the stone even past the 200mm mark that Jeff Farris said is the end of useful life? He based his knowledge, not just his opinion on the fact that the stone needs to be immersed in water. I have an older T7 and if the ability to raise the trough to utilize more of the stone is not correct, then that is a benefit without any value. Can you say useless affectation? Of course, the smaller the stone the more the concavity of the grind which is or might be a limiting factor as well. I forgot to add a couple of wisdom nuggets as well. No, you don't need a pick up truck to buy groceries but if you suddenly remember that you need a sheet of plywood it comes in handy. My favorite for last, even Tormek said the T4 is half of the T8. What is half of 8? Just kidding of course. In my life with my limited need for a Tormek, then T4 would have sufficed. I just hate "getting by" though.
Schmart,
You really understand the benefits of the T4. I wish the T4 and the T8 were priced the same. Then, people would compare them in terms of their individual needs. Those who prefer stationary more industrial machines would gravitate toward the T8. Those who wanted portability would gravitate toward the T4.
I have found portability increasingly important as I get older. Moving my Tormek often involves carrying it across my basement, up the stairs, and placing it in the back of my car. I do not move my T4 everyday or even every month, however, I am grateful for its lighter weight and smaller size whenever I do move it. This would not be much of an issue if I was thirty five. Quickly approaching seventy, it is an issue for me.
I have no experience with the Emco Star machine. Alf, I would encourage you to verify that the planer blades can be resharpened. I purchased the Tormek planer blade jig years ago, only to discover that my Delta "lunch box" planer blades could only be reversed once and then discarded. A recent member just had a similar experience with her Dewalt 735 planer. I hope your blades can be resharpened.
At its introduction in 2014, the T4 was the most advanced Tormek ever produced. Its revolutionary machined zinc housing with much improved accuracy was copied into the present flagship T8 model. I consider the other T8 improvements to be minor. We have been attaching magnets to our Tormeks for decades. I like the design of the T8's water trough, however, I have worked very well without it for years. I have two of the long ramps I have never used. I don't sharpen planer blades. The longest knife I have sharpened is eight inches.
I am a Tormek junkie. I have all of the jigs except for the profile cutter jig. How many people actually sharpen profile cutters, or even use them?
For the very odd time when one might want to use the ramp, I think a towel would suffice.
The T4 can certainly sharpen hand plane blades. I have reshaped a turning skew and a bowl gouge with my T4. The constraint with reshaping with any Tormek is the choice of grinding wheel, not the model of the machine. Rich, I must disagree with you about available grinding wheels for the T4. Tormek sells the DWF-200 and DWC-200 600 and 360 grit diamond wheels. Tormek chooses to only market them for the T2, however, they work very well with the the T4. They are "plug and play" with the T4. Venturing beyond Tormek, there is a variety of very good CBN wheels sized for the T4. The Norton 3X wheels in 46 and 80 grit are very fast cutting.
In my opinion, the SB blackstone is obsolete. I have never had success with it; it gums up. I will temper my statement by acknowledging that many skilled sharpeners, including you, like it. It has just never worked for me.
I believe the comments from the Tormek website are fast becoming outdated. I still like my original SG grinding wheel, however, in recent years I have been using diamond and CBN wheels more and more. Diamond wheels require a light grinding touch. The extra power of the larger motor offers no advantage with diamond wheels.
Alf, I would recommend you purchase a T8. No doubt, this is contrary to my posts. However, you have received enough information from other members and Tormek marketing casting doubt on the T4 that you would always wonder if you made the right choice. You do not need that doubt. You need full confidence in your Tormek. The T8 is the flagship. Hold off until you are comfortable budgeting the cost for it. Rich and Jeff are examples of very longtime Tormek users. A Tormek is a lifetime investment. Stick with Tormek quality. Also, Tormek's ironclad seven year warranty is formidable and will give you much peace of mind.
Best of luck with your Tormek journey. Keep us posted.
Ken
Hi All,
I impressed by the way members contribute and try to help. Thank you all for your feedback.
I try to cover all the issues pointed by those who took time to give their feedback. Portability is not an issue for me, because it is not my intention to travel with the T8, maybe I would move it sometimes in my workshop, which it should be no problem.
The prices of the grindstones; I am hoping that for what I am going to use this machine for, I think the original one that will be provided with the machine will last me for a long time, so probably it will the only grindstone I will owe. Water trough, it is a good point mentioned by Jeffs, even that if I do not have the option to raise the tank, putting some mass/piece of aluminium to compensate for the reduction of the stone will rise the water level back to touch the stone, IMO.
The Planer Blade attachment SVH-320 is the main reason I had my doubts on the T4, because since even Tormek do not recommend the use of the T4 for this Jig, it must be so, otherwise I am sure that the T4 would be fine for my needs, especially after all your feedbacks.
Now having said that I also made some calculation to compare the T4 with the T8. I have added the jigs I would need for my needs to both machines and compared the final price.
Planer Blade Attachment SVH-320
Included with the machine:
SG 250 Super-Grind-Stone
SE-77 Square Edge Jig
TT-50 Truing and Dressing Tool
SP-650 Stone Grader
WM-200 Angle master
Long Knife Jig SVM-140
Tool Rest SVD-110
The blue jigs are standard with the T8 the red ones are what I need to add. Tool Rest is important also because since I do some engineering, both with Lath and milling machine, I though at least I can use it for my metal machines.
and the Planer Blade Attachment because my Emco Star planer blades can be sharpened, I used to that on the sand belt that is part of the Emco Star.
The list for the T4 is different since not so much tools are included with it:
Planer Blade Attachment SVH-320
TT-50 Truing and Dressing Tool
SP-650 stone grader
WM-200 Angle master
SE-77 Square Edge Jig
Long Knife Jig SVM-140
Tool Rest SVD-110
Also the blue are included with the T4 and the red what I need to add, to have the same jigs.
Now when you add the total of both machines, I got a very interesting result :
T4 total cost is : €553,44
T8 total cost is: €688,72
Difference of: €135,28
So, IMO the difference is so small that to buy the T8 is the best option for just a € 135.28.
Now all I need is to convince myself that I need a € 700 sharping machine instead of my usual oil stones and glass paper that I am using now. 😊
Well thank you all for helping me to decide and evaluate my options.
Alf.
PS. Sorry for this long reply.I noticed that fter posating I lost the font colours that I used to indicate the differnt jigs, sorry
Hello.
If you planning to sharpen planer blades, who often are HSS steel, i will highly recomend by the T8 with the SB-250 stone.
I have sharpen a lot og planer blades, and the SG-250/200 stone will wear quickly when sharpening planerblades, and some of them are so hard that you wil need a SB stone.
Regards Even
Quote from: Even on May 29, 2019, 07:54:21 AM
Hello.
If you planning to sharpen planer blades, who often are HSS steel, i will highly recomend by the T8 with the SB-250 stone.
I have sharpen a lot og planer blades, and the SG-250/200 stone will wear quickly when sharpening planerblades, and some of them are so hard that you wil need a SB stone.
Regards Even
Thank you for your advise.
Alf
Thank you for your advise.
Alf
[/quote]
Andt with the t8 you wil get the TT-50 included, and that is very necessary when sharpening planer blades.
I and you wil also need a diamond plate #80grit or so to refresh the SB-250, becuse the stone quickly glazes, and you cant dress in with the orginal stone grader.
Even
Even, you are correct. Unless you only use diamond and/or CBN wheels, every Tormek, including the T4 needs a TT-50 Truing Tool. Even chisels and kitchen knives will eventually wear an SG grinding wheel out of true. I am convinced that Tormek designed the T4 package around a price point, to sell at $400 US or equivalent. Including the essential TT-50 would have added almost an extra $100 to the package cost.
Please do not misunderstand me. The T4 is a very well designed and manufactured machine; it is just not a machine which should be sold at $400. That is why I encourage prospective buyers to forget the price difference and decide on the intended work.
I emailed Wootz (Vadim at Knife Grinders) regarding a source for the 80 grit diamond plates. He sent me a link to the item on ebay Australia. I found the same item on ebay US yesterday, although they were out of stock. I checked back this morning and found that the 80 grit plates were available. I ordered two. Here is the link in Australia:
https://www.ebay.com.au/itm/Diamond-Plate-Stone-Knife-Blade-Sharpening-Whetstone-Polishing-Sharpener-60-3000/371947163036?hash=item5699c74d9c:m:mvZnN0ElE3gANdvGP-7OAHQ&frcectupt=true
Here is the US link:
https://www.ebay.com/itm/292421859240
Please note that the following is my opinion. Many years ago, Tormek switched from natural stones mined on a Swedish island to a man made aluminum oxide stone, the SG still in use. The SG is more coarse than the natural stone. That is both a blessing and a curse. The coarser SG cuts more quickly, however, it would not leave as smooth a finish. Some clever person at Tormek realized that a double sided silicon carbide stone could regrade the SG finer. The coarse side could almost restore the coarser grit.
Whether the stone grader was specifically designed for the task or a standard hardware store item, it did the job of making the SG finer.
The SB and SJ wheels were introduced almost ten years ago. In the last ten years, diamond plates have been introduced for dressing Tormek wheels. These advances have largely happened on this forum by two notable pioneers: Ionut, who has unfortunately moved on to other interests; and Wootz (Vadim of Knife Grinders). Fortunately, Wootz is an active poster and responsible for many of the recent refinements in knife sharpening.
In my ten years as a Tormek user, I have been impressed with the many truly remarkable innovations from Tormek. Borrowing a quote from the Americas cup racing, "There is no second place." Tormek is the world leader in wet grinder sharpening. However, with all of the advancements, there is still room to improve. I put the stone grader in the awaiting improvement category. I also put the SB and SJ in the category of having untapped potential. I hope we will someday unlock that potential.
Ken
EDIT: The ebay seller advised me that the 80 grit is out of stock. He does not know when they will be available again. I asked him to advise me when the 80 grit is available. In the meantime, I have ordered a double sided 150-600 grit plate. I will test it and post my results. Stay tuned.
Thank you Ken for youtr advice, inforamation and time to reply.
Alf
When I was looking to by a Tormek I went through a similar thought process and after adding up everything I went with the T8. I am pleased with my decision.
In addition to this forum here are some sites I have bookmarked. I find them invaluable as a reference:
http://knifegrinders.com.au/
https://www.youtube.com/channel/UCrs9DEOG9tHbxAH50CKINqA
http://www.sharpeninghandbook.info/
The DVD supplied with the T8 is a great place to start. You will learn the fundamentals of sharpening from the experts. You can produce an extremely sharp edge with just the standard wheel and leather hone. I would suggest becoming skilled with this combination before adding the extras.
Quote from: john.jcb on May 31, 2019, 04:02:21 PM
When I was looking to by a Tormek I went through a similar thought process and after adding up everything I went with the T8. I am pleased with my decision.
In addition to this forum here are some sites I have bookmarked. I find them invaluable as a reference:
http://knifegrinders.com.au/
https://www.youtube.com/channel/UCrs9DEOG9tHbxAH50CKINqA
http://www.sharpeninghandbook.info/
The DVD supplied with the T8 is a great place to start. You will learn the fundamentals of sharpening from the experts. You can produce an extremely sharp edge with just the standard wheel and leather hone. I would suggest becoming skilled with this combination before adding the extras.
Thank you John for your help and links, which I will look into for sure.
Final it arrived.
Do I need to check or give any oil to the machine before I start please?
Alf
Quote from: dusmif on June 12, 2019, 05:24:07 PM
Final it arrived.
Do I need to check or give any oil to the machine before I start please?
Alf
Before you start you need to oil the leather wheel in accordance with the Tormek instructions and add your first bit of honing compound. Then add water to the tray and you are ready to start sharpening. I started by sharpening some cheap kitchen knives I have for camping. You will be amazed how fast your confidence grows and how what you hear in the videos makes sense. The Tormek videos are a great start and I followed them for some time before I began trying additional products such as the FVB.
Quote from: john.jcb on June 12, 2019, 07:15:14 PM
Quote from: dusmif on June 12, 2019, 05:24:07 PM
Final it arrived.
Do I need to check or give any oil to the machine before I start please?
Alf
Before you start you need to oil the leather wheel in accordance with the Tormek instructions and add your first bit of honing compound. Then add water to the tray and you are ready to start sharpening. I started by sharpening some cheap kitchen knives I have for camping. You will be amazed how fast your confidence grows and how what you hear in the videos makes sense. The Tormek videos are a great start and I followed them for some time before I began trying additional products such as the FVB.
Thank You John,much appreciated.
So the shaft does not need any lubrication before first star?
Alf
Dusmif,
When I first got mine there was no lubrication needed for the shaft. As John said just oil the leather wheel and apply a generous amount of compound and even it out with something flat like a chisel or side of a butter knife. On mine anyway I had to use more oil on the leather than the recommended 2/3 tube, I had to use almost the whole tube.
Antz
PS: don't throw away the shipping sleeve that came on the shaft! You'll need it if you want to run the machine without the stone and just the leather wheel. Just remove the stone and put the sleeve back on and tighten the eze lock. It'll keep the shaft from shifting. Trust me I learned the hard way.
Thank You Antz, that was very helpfull.
Alf.
Antz makes a very good point about saving the grinding wheel spacer (shipping sleeve). If you did not keep it, a very adequate substituts spacer can be quickly made from a short piece of plastic pipe, tubing or a dowel with a hole drilled through it. Add my name to those who learned this the hard way.
Ken
Adding white lithium grease to the shaft bushings is a good idea.
I agree, Rich. I keep a small tube of white lithium grease with my Tormek kit. (A small tube will more than outlast me.)
Ken
As a person that used a Baldor Bench Lathe 12 hrs a day for ~25 years, the 30 minute per hour really puzzles me for a $400+ setup. What I find strange on the T-4 (maybe the 8 is same?) is the Stone wheel shaft just uses plastic bearings. Why no roller bearings? At the 120 RPM , they'd last indefinitely most likely. Would be a interesting modification, has anyone done it?
My understanding is that the rated "use time" of 30 minutes each hour is no longer relevant to the new model of the T4.
The older T4's had plastic cases that were susceptible to heat issues, whereas the current ones have a cast zinc housing that is impervious to the heat generated by the motor and works.
The rating would obviously still apply to the older T4's, but does not apply to the new ones with the zinc case.
I wish Tormek Marketing would update the handbook and website about this thirty minute situation. I have read every post on this forum for the past ten years. I do not recall a single post where the poster overheated a T4 motor. In fact, I spent a day with the Tormek demonstrators at a woodworking show several years ago. They were running a T7 and a T4 essentially continuously all day. Throughout the day, I placed my hand on the zinc top of the T4. It was barely warm, certainly not hot.
The predecessors of the T4 were the T3 and the T1200. They both had all plastic housings. I have been told that the all plastic housings retained heat and that with prolonged use, it was possible for the housing to melt. I have not seen any posts or other documentation to confirm this, although it seems a logical possibility. My 2009 handbook only lists the T1200 with a European 240 Volt 50 Hertz motor. The T3 was not widely marketed in the US. This forum was founded by the US Tormek agent. The "Tormek" was the larger SuperGrind and T7 on the forum back then.
Beginning in 2014, the introduction of the T4 changed that. The all plastic housing of the T3 was totally redesigned to include the machined zinc top. The marketing claim was a "300% increase in accuracy". While I do not understand the math involved, I do not doubt the claim. The entire top, including the four sleeves for the support bar, is all one precision machined piece. It is a true advancement in several ways. Tormek later used this zinc housing idea with the present flagship T8 model. It is the main difference between the T7 and the T8. It also acts as a radiator, helping to cool the motor, thus solving the thirty minute "problem".
Some may protest that the T4 motor is not listed for continuous duty. This is technically correct. The blower motor on my home furnace is rated continuous duty. It is set to run 24/7 all year long to keep the air circulating. How many of us, even in our wildest "busy professional sharpening service" dreams would leave the Tormek running all night or even during lunch?
I do not know a reasonable continuous run time limit for the T4. I do know that it is much longer than thirty minutes. I also know that I will need a break long before my T4 needs one.
Ken